The present invention relates to pen plotters, and more particularly, to a system for marking plotting media in a pen plotter wherein vaporized ink is delivered to an aerosol pen which applies the vaporized ink to the plotting media surface in a precision, controlled spray.
In a traditional pen plotter, an ink-containing pen is carried by a pen carriage over the surface of the plotting media. The pen has a plotting tip communicating with the ink contained within the pen which forms the plotting lines on the media when the tip is lowered by the pen carriage into contact with the media. This means of applying plotting lines presents difficulties when dealing with delicate or abrasive plotting media where the tip cannot glide smoothly over the media surface. The plotting tip may bunch or tear delicate media or, if the media is unusually absorbent, ink blotching may occur during momentary pauses of the pen carriage. Also, if the pen tip crosses a recently plotted line, the previously applied ink may still be wet rendering the media especially susceptible to tearing or damage. Abrasive media may damage the tip of the plotting pen causing irregular or oversized plot lines and ultimately requiring premature replacement of plotting pens. When plotting with multiple colors, whether delicate or sturdy plotting media is used, when the plotting tip crosses a previously plotted line of a different color, the pen tip can pick up some of the previously applied ink, smearing it into the present plot line. This is especially true if lighter colors are plotted after darker ones. This tends to foul the tips of the lighter pens, requiring their replacement.
Because ink flows from plotting pens at a constant rate, pen speeds must be maintained at below a maximum rate to prevent inconsistencies and skipping in the plot lines. Thus, plot generation times are constrained by the rate at which ink will consistently flow from the tips of the plotting pens. Moreover, if the plotter is not dynamically re-programmable in the speed of its relative pen movement over the plotting media, the speed must be set to the maximum speed for the slowest pen tip type.
In order for traditional plotters to generate drawings depicting fill-in, gray scale, or shading, areas must be filled in. Filling in the entire area, multiple shade lines or cross-hatching is normally the preferred method. This consumes large amounts of ink, and to plot such features requires numerous, repetitive pen carriage movements, which increases plot generation time.
Wherefore, it is an object of the present invention to provide an effective technique/system for applying ink to a diverse range of plotting media which does not require contact between the ink administering device and the plotting surface, thus alleviating many of the complications and problems associated with traditional contact pen plotters.
It is another object of this invention to provide an effective technique/system for applying ink to plotting media whose ink delivery rate can be varied in order to effect faster plot generation speeds and shorter plot generation times.
It is still another object of this invention to provide an effective technique/system for applying ink to plotting media which can effectively and quickly perform plot area fill-ins and gray scaling.
It is yet another object of this invention to provide an effective technique/system for applying ink to plotting media in which wearing and broadening of a contacting tip is not a factor in pen life and replacement time.
Other objects and benefits of the invention will become apparent from the detailed description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.